1. Technical Field
The present disclosure relates to a liquid crystal display device, and more particularly, to a thin film transistor array substrate of a liquid crystal display device having color filters and a method of fabricating the same.
2. Discussion of the Related Art
Since flat panel display devices are thin and light, and have low power consumption, the flat panel display devices are used for portable display devices. Among the flat panel display devices, liquid crystal display (LCD) devices are used for laptop computers, desktop computer monitors, and televisions.
The LCD devices include a first substrate having color filters and a second substrate having switching elements and pixel electrodes. The first substrate and the second substrate are spaced apart and face each other. A liquid crystal material is interposed therebetween. On the first substrate, a black matrix and a color filter layer are formed in an array matrix including a plurality of red, green, and blue color filters surrounded by corresponding portions of the black matrix. A common electrode is formed on the first substrate and covers the color filter layer and black matrix. On the second substrate, a plurality of thin film transistors is formed in a shape of an array matrix corresponding to the color filter layer. A plurality of gate lines and data lines cross one another such that each thin film transistor (TFT) is located adjacent to each intersection of the gate lines and the data lines. A plurality of pixel electrodes are formed on a pixel region. The pixel electrode is formed of a transparent conductive material having high transmissivity, such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). The liquid crystal molecules of the liquid crystal material layer are aligned and arranged by the operation of the thin film transistor. An incident light passing through the liquid crystal layer is controlled to display an image.
When fabricating the LCD device, the first substrate is aligned with and attached to the second substrate. The first substrate and second substrate are assembled after being formed separately. During the separate forming processes, the first substrate is treated with heat processes such as, for example, a pre-bake process, exposure to light, or a post-bake process for forming color filters. The heat processes may result in deformation of the elements of the first substrate, which causes misalignment when assembling the first and second substrates.
When the first substrate is misaligned with respect to the second substrate, then a light leakage occurs in the completed LCD device. For example, on the first substrate, the black matrix is formed on the entire surface of the first substrate and has openings corresponding to the pixel electrode of the second substrate. The black matrix prevents light leakage in the LCD panel except for the openings corresponding to the pixel electrode. The black matrix protects the thin film transistor from the light such that the black matrix prevents generation of a photo-current in the channel area of the thin film transistor. The black matrix needs an enough alignment margin to prevent light leakage. When there are errors in the alignment margin of the black matrix, the light leakage occurs, thereby deteriorating display quality of the LCD devices.
A color filter layer can be formed in the array substrate to reduce the misalignment. However, a short circuit between the gate metal layer and the data metal layer, and a high parasitic capacitance between the gate metal layer and the data metal layer may still occur. The parasitic capacitance causes cross talk.